Owl location Flashcards
(23 cards)
Do owls use vision to hunt
No! They could do it in the dark/struck the leaf if it rustled (not the mouse)
Is aud. map caluclated in cochlea?
No, cochlea only has amplitude and frequency.
Aud Map calculated higher up (ICX)
Knudsen Konishi magnet coil experiment (basic finding?)
localize sound with audio and head turning, not visual
Facial ruff, explain directions
Ears asymmetrical, right ear does upward sounds, left ear does downward sounds
RUFF = (RU, right up)
how is elevation and azimuth calculated owls
Elevation by ILD (ruff), Azimuth by ITD (ONGOING disparity, not on/offset)
Basic Path for owls
N. magno/angularis TO
N. laminaris TO
ICC TO
ICX TO
Optic Tectum
Where is aud map first seen
ICX
EXCLUSIVELY BINAURAL tuned to COMBO OF ITD AND ILD
ICX Receptive Field
ICX neurons have receptive field for ITD/ILD, azimuth and elevation “best area”
HAVE SURROUND INHIBITION = SPATIAL SHARPENING
Parallel Pathway evidence in owls
Lidocaine numbing to angularis only disrupted ILD, left ITD alone because parallel in mangocellularis
Delay Lines, explain what this does
To code ITD, delay lines coming from IPSILATERAL MAGNOCELLULARIS going to the LAMINARIS
Coincidence detector in laminaris
Where is phase locking
in n. magnocellularis NOT IN ANGULARIS, Phase locking to encode ITD precisely
Describe N. laminaris coincidence detector
ITD for multiple frequency bands
mulitple coindice detector
this is so when get to IC, map of ITD
Phase ambiguity, why problem/how solve
If pure tone, time it takes to get to other ear becomes simultaneous,
FIRE AT 0TD, +/- PERIOD
Solved because IXC SUMS OVER FREQS and most natural sounds complex
Convergence of what from ICC to ICX?
Same ITD over all freqs gets averaged
NO FREQ CODING IN ICX, only ITD and ILD
ICC had freq and ITD
What area controls head-turning orientation
Optic Tectum is sensoritmotor, takes in visual and auditory senses and puts out motor signals
Aligning auditory map how?
Visual info drives the alignment, computed from ITD/ILD
Results of plugging ear in localization and in juvenile owls
Plug right ear = think sound is LOWER because left ear louder
vice versa for left
IN JUVENILES - adjust to these abnormal cues because VISION GUIDES AUDITORY, learn to correct it
If blinders placed over eyes, never correct
Describe prism orienting behavrios throughout experiment
0 days = normal to aud/visual stimulus
Day 1 = visual affected immediately, aud not
Day 42 = visual and aud both affected
Post removal = visual normal, aud still affected
VISION DRIVES AUD, aud takes time to adjust
Describe Optic Tectum receptive field shifts
OT has a receptive field of vis/aud
Visual part shifts first, like orienting behavior
Then aud shifts later in prism experience
Critical period for ITD calibration in OT
If juveniles had experience with prisms, then they shift their ITD later too
Adults without experience don’t shift their Aud receptive field, need exposure as juvenile
Where does the ITD shift occur
ITDs change in the ICX
ICC normal
It’s how the synapses from the ICC connect to the ICX
Describe how the ITD shift occurs over time
During beginning phase, there’s a “TRANSITION” period where ICX is tuned to both NORMAL and AFFECTED ITD values
Then later, they are fully shifted to AFFECTED ITD tuning
Anatomical shifts in ICX ITD Tuning
New synapses use NMDA Receptors
Old synapses use AMPA Receptors
GABA synapses SUPPRESS OLD tuning
